Supercharger



Patented June 22, 1937 UNITED STATES PATENT OFFICE SUPERCHARGER SanfordA. Moss, Lynn, Mass., assignor to General Electric Company, acorporation of New York The present invention relates to internalcombustion engines with superchargers of the centrifugal compressor typewhich are driven from and form a part of the engine and which are driventhrough suitable gearing from the engine crank shaft. The invention'iswell adapted for use in airplane engines although it is not limited tosuch use necessarily. l

In connection with the operation of supercharged internalcombustion-engines, it is desired often to provide the engine withdifferent amounts of supercharging. This is accomplished by changing theratio of the gearing between the .engine crank shaft and the impeller ofthe 1 supercharger so as'to operate the impeller at different speeds: Indoing this, however, the

difflcultyis met' with that, due to the inherent.

characteristics of a centrifugal compressor, the

compressor is not used always at its best efil-' 20 ciency; Acentrifugal compressor comprises an impeller which receives air at itscentral portion and'discharges it at its periphery to a diffuser inwhich velocity-"of the-air is converted into pressure A diffuserdesigned for use with an 25 impeller operated atone speed isno tequallyefficient when the impeller is operated at another speed. Accordingly,itis desirable, when in. connection with a particular engine, adifierent gear ratio'is' adopted, to provide a diffuser suited to 30 thenew operating" conditions. However, with the centrifugal compressorbuilt in and forming a part of an internal'COmbus'tion engine, it hasnot been-possible in constructions used prior to my invention, to changethe diffuser when a dif- 35 ferent gear ratio was adopted Withouthavingto change expensive engine casting s,.a thing often notpracticable.

The object of my invention is to provide an 40 improved constructionandarrangement of (11- w rectly-driven centrifugal compressors whereinthe diffuser may be changed readily and without hav ing to makeexpensiveengine castings. Fora, consideration of what I believe to, be no'vel and45 my invention, attentionis directed to the ,foll'owf. ingspecification and the claims appended thereto.

In the drawing,- Fig. 1 is a sectional view of an.

internal combustion engine provided .with a di rectly-drivensupercharger "embodying my invention; Fig. 2 is a side view, partlybroken away, of

the diffuser shown in Fig. 1, and Fig. 3 is an eniarged sectional viewalong line 33 of Fig. 2.

The arrangement illustrated in the drawing comprises an internalcombustion engine-having 55 an engine or crank casing wall ill with anopening I I in which a crank or engine shaft I2 is supported by a rollerbearing 13. Otherdetails of the engine proper, such ascylinders,-valves, etc., are not shown as they are well known and haveno particular bearing on the present invention. 5 A built-insupercharger for supercharging the engine is secured to the crank casingand driven from the crank shaft l2 by means of a shaft 14 connected tothe crank shaft by splines l5. The supercharger has a casing comprisingtwo sections l6 and I! with flanged portions l8 and I9 respectively. Thesection 16 has an annular flange 20 adjacent the crank casing wall Inand rigidly secured thereto by aplurality of bolts -2l Each section hasan inner wall portion 22 and 23 respectively, an outer wall portion 24and 25 respectively andan intermediate. wall portion 26 and 21respectively. The intermediate wall portions 26 and 2'! usually areintegrally united with the'corresponding inner and outer wall portions.20 The inner wall portion 23 forms an annular inlet chamber 28 and theinner'wall portions 22 and 23 define an annular impeller chamber 29. Theouter wall'portions 24 and 25 define an annular compression oroutletchamber 30; Regarding 25 the dimensions of these chambers it-will benoted that the mean. axial widthof the outlet. chamber 30 ;isconsiderably, greater than the axial width of the-outlet portion of the.impeller chamber 29. The inletchamber .28:-has-a.fianged conduit por- 30tion 3| which is.usually;:connected to an inlet 32.. The inlet32Tthrough the intermediary'of a carbureter 33 usually has an opening 33which in. the case of an airplane engine opens in the direction ofairplane travel. The outlet chamber 35 30, is connected to aconduit orconduits 34.; for dischargingamixture of, compressed air and fuel tocthecylinders (not shown.) .of. the internal combustion engine. An impeller35 with. a plurality of blades 36 is disposed within the impellerchamber 29., Theimpeller is drivenfrom the. shaft l4 through theintermediary of a gearing ror gearings 37 and a" shaft 38. The latterisconcentrically arranged withthe shaft. l4 and supported by a ballbearing 39' secured to the casing half I G and a rollerbearing40.secured to the casing half ll. Packings 4| 1and 42 are arrangedadjacent the bearings 39-and40 respectively to prevent lubricant'fromleaking into the impeller chamber. tatable deflector 43 which has athreadedsurface adjacent a plane surface of a cylindrical packing member44. The deflectors are threaded in a direction to return leakage oil tothe bearings. Leakageof lubricant into the impeller chamber 65 Eachpacking includes a roe is further minimized by the provision of meansfor maintaining atmospheric pressure in the packing space or spaces,nearest to the impeller chamber. These means include a vent, 45 and 46respectively, for each packing. One end 41 of each vent communicateswith one of the packing spaces and the other end 48 of each ventcommunicates with the atmosphere. A member 50 of the impeller is rigidlysecured to the shaft. The end of the shaft facing away from the crankcasing wall I is united with a pinion which meshes with a gear'52 on arotatable shaft 53.

A pinion 54 of the gearing 31 is loosely provided on the shaft 53 andmeshes with a gear 55 secured to an end portion of the shaft id. Thegearing may also include a suitable slip clutch 56 diagrammaticallyindicated in the drawing air mixes with fuel in the carbureter, whencethemixture or medium of air and fuel passes through the inlet chamber 28into the impeller chamber 29. The rotating impeller blades 35 add energyso that the mixture is discharged from the impeller chamber at highvelocity.

A diffuser 51 is provided at the outlet portion of the impeller chamberfor converting velocity energy of the impelled mixture or medium intopressure energy. and discharging the compressed mixture or medium intothe discharge chamber 30. The diffuser in accordance with my inventionis provided as a separate, detachable element. It comprises side walls58 and 59 which are integrally united with a plurality of vanes 50. The

inner annular portion of the side wall 55 of-the diffuser is seated onthe seating surface GI and an inner portion of the side wall 59 isseated on, the seat 52 of the intermediate wall portion 21.

The arrangement is such that the inner surfaces 53 and 55 of the sidewalls 58 and 59 form smooth continuations of the inner surfaces of theinner and intermediate wall portions 22, 23, 26 and 21.

An outer annular portion of the diffuser is disposed within or projectsinto the outlet chamber 30. The diifuser is rigidly held on the seatingsurfaces of said intermediate portions by a plurality of detachableconnecting means, in the present instance shown as a plurality of bolts55. Each bolt projects into a bore 56 in the casing section IS, a bore51 in the side wall 58 and a vane 60 of the diffuser, and a threadedbore 58 inthe casing section 11. The bolts 65 have a loose fit in thebores 55 and 61 ofthe intermediate casing wall portion 21 and the vanes50 respectively. Thebolts 65 secure the diffuser to the superchargercasing and at the same time they unite the two casing sections I 6 andI1 by forcing the adjacent surfaces of the flanged portions 18 and i9towards each other. It is noted that the outer surface of the diffuserside wall 59 (Fig. 3) is spaced from a shoulder 1| formed at the end ofthe seating surface 62. Tightening of the bolts 65. causes the shoulder1| to be drawn towards the surface 10 until a tight fit is attainedbetween the edges 12 (Fig. 3) of the vanes and the inner surface of theintermediate wall portion 21. The flanges l8 and iii of the two casingsections are united by additional bolts 13. Tightening of the bolts 13causes cylindrical surfaces of the flanges to engage each other. Thus,the two sections of the casing flrmly close the joint defined by theflanges I8 and iii. The fastening together of the flanged casingsections represents an additional means for firmly holding the diffuserbetween the two casing'sections, which in certain cases permits theomission of the bolts 65.

The provision of a diffuser as a detachable element in built-insuperchargers of combustion engines has 'a distinct advantage in that itincreases to a considerable extent the adaptability of such arrangementsto different operating conditions. For example, in the case where anairplane engine has to be rebuilt for a different use, such as normalflying at higher or lower altitude, all that is necessary is to replacethe gearing 31 by a gearing with a different ratio and at the same timereplace the diffuser by a diffuser with a different vane arrangementwhereby the supercharger may be operated at maximum efliciency with thenew gear ratio. More specifically, if in an airplane engine withbuilt-in supercharger the gear ratio and diffuser are such as to givethe desired amount of superchargin'g at maximum efliciency under normalflying condition at an altitude of 3000 feet, such engine can be easilyadapted to flying condition at 10,000 feet altitude by replacing thegearing and the diffuser to obtain the desired relatively greatersupercharging efiect at maximum efliciency at the altitude of 10,000feet. With my improved arrangement it is no longer necessary to replacethe entire supercharger or the engine in order to render an airplaneadaptable to a different normal operating condition.

What I claim as new and desire to secure by Letters-Patentbf the UnitedStates, is:

1. In a supercharger for internal combustion engines, the combination ofa casing having inner wall portions defining an inlet chamber and animpeller chamber, outer wall portions defining an outlet chamber, andintermediate wall portions secured to the inner and outer wall portionsand defining *a seat for a diffuser, a shaft, an impeller with'aplurality of blades being disposed within the impeller chamber andsecured to the shaft, a diifuser having a side wall and a plurality ofvanes integrally united with the side wall, the

diffuser. side wall being seated on said seat, and

means for detachabiy securing the diffuser to said intermediate wallportions comprising a plurality of bolts, each bolt projecting through abore in at least one of the intermediate walls and one vane.

2. In a supercharger for internal combustion engines, the combination ofa casing comprising two sections defining an impeller chamber and anoutlet chamber, means for conducting a fluid to the impeller chamber, ashaft, an impeller dis- SANFORD A. M055.

